xapi/nm: Send non-empty dns to networkd when using IPv6 autoconf

Because Autoconf is not DHCP, networkd uses the dns value to write to
resolv.conf. This is done on ocaml/networkd/bin/network_server.ml line 745

This allows to have non-empty resolv.conf when using IPv6 autoconf.

Signed-off-by: Pau Ruiz Safont <[email protected]>

Author: psafont

ocaml/xapi/nm.ml

@@ -634,6 +634,7 @@ let bring_pif_up ~__context ?(management_interface = false) (pif : API.ref_PIF)
                     rc.API.pIF_ip_configuration_mode = `Static
                 | `IPv6 ->
                     rc.API.pIF_ipv6_configuration_mode = `Static
+                    || rc.API.pIF_ipv6_configuration_mode = `Autoconf
               in
               let dns =
                 match (static, rc.API.pIF_DNS) with